Metabarcoding Analysis of Diet Diversity of Mesopelagic Fishes and Salps

Food web interactions of pelagic ecosystems of the deep open remain largely unexplored and unknown. We report results of molecular (DNA metabarcoding) analysis of the diets of mesopelagic fishes and salps collected from the NW Atlantic Ocean Slope Water during Summer 2018 and Spring 2019. Metabarcoding allows detection and taxonomic classification of consumed prey, including tiny, fragile (gelatinous), and difficult-to-identify organisms. Mesopelagic fishes predominate the biomass of the ocean twilight zone and are coming under increasing scrutiny as a target for commercial fisheries. Comparative DNA metabarcoding and morphological taxonomic analysis of fish gut contents has yielded detailed understanding of the essential food resources for this exceptional productivity. DNA metabarcoding of salp gut contents is providing new insights into diet diversity and trophic interactions of salp species. Integrative and comparative molecular and morphological analysis will provide new understanding of the structure of mesopelagic food webs, and new insights into the dynamics and responses to climate change of these deep sea ecosystems.